SPH^ROPHORACE^. 



[ 588 ] 



SPH^ROPLEA. 



depressed, with a simple ostiole ; spores 

 almost linear, simple. 



XXIV. DiLOPHOspHORA. Conccptacle 

 immersed in a spurious stroma, covered, 

 perforated by a pore ; spores cylindrical, 

 continuous, crowned at both ends with ra- 

 diating filiform appendages. 



XXV. Sph^ropsis. Conceptacle sphe- 

 rical, immersed, subinnate, astomous, at 

 length (by the separation of the epidermis) 

 bursting by circumscissile dehiscence or ir- 

 regularly. Spores simple. 



SPH^ROPHORACE^.— A family of 

 Angiocarpous or closed-fruited Lichens, cha- 

 racterized by their apothecia formed in the 

 swollen points of the thallus, bursting irre- 



British Genus. 



SPH.EROPHORON. — Thallus erect, 

 shrubby, externally crustaceo-cartilaginous, 

 internally solid and cottony. Apothecia ter- 

 minal, spherical, the perithecium, formed of 

 the thallus, closed, dehiscing irregularly. 

 Nucleus globular, internally floccoso-cartila- 

 ginous, the discharged (black) sporidia 

 crowded in the circumference. 



S. coralloides (fig. 399. page 388) is not 

 uncommon on sand-rocks, among mosses. 



S. compactum is less common. The sper- 

 mogonia have only been discovered as yet in 

 the latter j they occur at the ends of the 

 more delicate branchlets of the thallus. 



BiBL. Hook. Brit. Flor. ii. pt. 1. p. 236; 

 Leighton, Brit. Angioc. Lichens ; Tulasne, 

 Ann. des Sc. nat. 3 ser. xviii. p. 209. pi. 15. 



SPH^ROPLEA, Ag.— A genus of Con- 

 fervaceae of uncertain position, but proba- 

 bly allied to the Zygnemacese. It is cha- 

 racterized chiefly by the formation of the 

 spores. The plants consist of simple jointed 

 filaments, with long articulations, at first 

 containing green colouring matter, excavated 

 by large vacuoles, producing a banded ap- 

 pearance (PI. 5. fig. 14 a), the contents 

 finally resolving themselves in the fertile 

 cells into numerous spinulose globular spores, 

 arranged iu longitudinal rows {b), which be- 

 come red when ripe. 



The development of the spores of S. annu- 

 lina has been observed by several authors ; 

 and Colm has recently published an account 

 of the formation of spermatozoids in distinct 

 cells, exercising a fertilizing function. The 

 filaments (which always terminate in pointed 

 hair-like ends) present, when actively vege- 

 tating, the excavated or banded appearance 

 of the green contents above noticed ; the 

 vacuoles separating the bands have a proper 



colourless mucilaginous coat. When about 

 to produce spores the regularity of the bands 

 vanishes, the vacuoles multiply in number in 

 the substance of the bands, and the contents 

 present the appearance of a green /ro^A, with 

 starch-granules scattered through it. After 

 a time a number of green corpuscles (the 

 spores) appear in the median line of the cell; 

 these assume a stellate shape, with radiating 

 threads of protoplasm connecting them to- 

 gether ; they soon appear in pairs, separated 

 by transverse false septa, formed by the 

 flattened vesicles of the vacuoles. The spores 

 gradually become better defined, and the 

 false septa disappear; then the young spores 

 present themselves as globular bodies, de- 

 void at this time of a cellulose coat. From 

 two to six minute orifices are j^erceptible at 

 this time in the partially softened wall of the 

 parent-cell. While these phaenomena are 

 occurring in some of the cells, a diff'erent 

 change takes place in others. The green 

 bands assume a reddish-yellow colour, their 

 starch disappears, and they are gradually 

 converted into myriads of short stick-shaped 

 bodies, which break apart and " swarm " in 

 vast numbers, filling the whole cell, moving 

 actively in all directions. The gelatinous coat 

 of some of the vacuoles sometimes remains 

 intact, and these then lie free in the cavity 

 of the cell, and are often carried about by 

 the rapid motion of the corpuscles. Orifices 

 are meanwhile formed in these cells also, 

 through which the stick - shaped bodies 

 (spermatozoids) escape into the water. Their 

 length is about 1-3000". Their hinder end 

 now appears somewhat swollen, and they 

 bear two long cilia on the pointed beak ; in 

 fact resembling the microgonidia of the other 

 Confervoids. Cohn states he has seen them 

 accumulate around the orifices of the spore- 

 cells, enter into the cavities of these, and 

 swarm about in the interior, in considerable 

 numbers, at length adhering to the young 

 spores. The spores then acquire a mem- 

 brane, and under this a second, which 

 is at first smooth, but afterwards presents a 

 spinulose or stellate appearance; the first 

 coat is then thrown ofi^, and a third, smooth 

 coat appears under the stellate coat, closely 

 investing the contents. These conditions 

 resemble those of the spores of Spirogyra 

 and other Confervoids ; Spirogra, however, 

 retains the outer coat until germination. 

 The green contents of the spores ultimately 

 turn red. Their size and number in a cell 

 vary much. 



Cohn has also observed the germination 



